The term, “poisonous priority”, is a relatively recent term used to describe an unusual phenomenon encountered in Europe where a claim in a patent or application is found to be anticipated by the application from which it claims priority or, in the case of divisionals, where a parent application is found to be anticipated by its divisional or vice versa. It is clear from the commentary on a number of European IP blog sites, such as Tufty the Cat1 and IPKat2, that there are different views within the patent profession as to whether or not this is a desirable outcome. As will become evident in the article below, I believe that this outcome is extremely undesirable and contrary to the spirit of the Paris Convention. Unfortunately, poisonous priority, or "toxic priority" as it is sometimes called, has now come to Australia and New Zealand. In Australia, the cause was a decision of the Full Federal Court of Australia (five judges sitting) in AstraZeneca AB v Apotex3 handed down on 12 August 2014. In New Zealand, the cause was commencement of the Patents Act 2013 on 13 September 2014.
How does poisonous priority arise?
Poisonous priority arises in “whole of contents” novelty jurisdictions where a patentee or patent applicant relies on multiple priorities or partial priority to support a single claim, and where the relevant patent law does not include effective protection against self-collision, or a mechanism for effectively assigning different priority dates to different forms or embodiments of the invention encompassed by the claim. For anticipation to occur there needs to be a second application in the same jurisdiction relying on the same sources, or at least overlapping sources, for priority purposes. This occurs most commonly when a divisional application is filed, but it can also occur when two applications are filed in the same jurisdiction on the same day claiming the same priority, or where the priority application is itself an application, other than a provisional application, filed in the same jurisdiction.
In the circumstances set out above, any claim which is not “pure” in a priority sense, in that it claims multiple priorities or partial priority, is likely to be anticipated by one or all of the related applications or patents. The problem can be illustrated with a simple example ("Scenario 1").
An applicant files a priority application in respect of invention A. Within 12 months the applicant files a PCT application in respect of invention A+ (expanded broader version of invention A) and invention B. Since there is no prior art, and the only objection is a unity of invention objection, the application proceeds to allowance with a claim to A+ after the claims to invention B are deleted. The applicant also files a divisional with the same specification but including claims directed to invention B. Without a mechanism for attributing the earlier priority date to the claim to A+ insofar as it encompasses invention A disclosed in the priority application, the priority date of the accepted claim to A+ will be the date of filing the PCT application. Applying whole of contents novelty principles, the disclosure of invention A (as a part of invention A+) in the divisional application would support a claim to invention A, and such a claim would be entitled to the earlier priority date. Since invention A falls within the scope of the claim to invention A+, the divisional anticipates the claim to invention A+ in the parent under whole of contents novelty. This will be the case even if the divisional application does not include a claim to invention A, since a whole of contents novelty objection is based on the whole disclosure of the cited application, not just the claims.
Depending on the applicable law, there are a number of ways that the applicant or patentee could attempt to amend the claims to avoid this consequence, for example by splitting the claim to A+ into two claims, a claim to invention A and a separate claim to +, i.e. the additional subject matter added to the PCT application. There may be other amendment options depending on the jurisdiction, and these will be discussed below. However, before discussing the applicable laws in detail, it is worth giving some attention to the Paris Convention, in particular Articles 4F and 4G.
The Paris Convention – Articles 4F and 4G
The Paris Convention of 1883 introduced a six month period for claiming priority for patents, trade marks and designs. According to the Paris Convention at that time, if a patent application is filed in one contracting State, a right of priority will be enjoyed if the applicant filed an application in another contracting State within six months. Since that time, the Paris Convention has been amended several times, with provisions relating to multiple priorities, partial priorities and the filing of divisionals being subsequently included. In 1900 in Brussels the six month period was extended to the twelve month period for patents we know today. A summary of the amendments leading up to current Articles 4F and 4G is provided below:
The Hague Conference 1925
Article 4F was introduced to allow an applicant to file a divisional application if the application relied on multiple priorities or examination revealed that the application was complex.
London Conference 1934
Article 4F was amended to allow a single patent application to claim multiple priorities, provided that there was unity of invention. In other words, where a single application claims priority from more than one priority application, it is possible to maintain the priority claim to the multiple priority applications in a single application if the claims satisfy the test for unity of invention. The reference to the filing of divisional applications was moved from Article 4F into new Article 4G which preserved the opportunity for an applicant to file one or more divisional applications while retaining, where applicable, the benefit of the right of priority.
Lisbon Conference 1958
Article 4F was amended to recognise partial priority. Prior to this amendment there was a concern that when filing an application under the Paris Convention it was necessary for all subject matter claimed to be found within the disclosure of one or more of the priority applications. This amendment introduced the ability for an applicant to add new disclosure to the Convention application itself. The requirement for unity of invention was retained, as was Article 4G and the ability for an applicant to file one or more divisional applications retaining, where appropriate, the right of priority. Article 4G was also amended to provide for voluntary divisional filings.
The current text of Articles 4F and G is set out below:
4 F. No country of the Union may refuse a priority or a patent application on the ground that the applicant claims multiple priorities, even if they originate in different countries, or on the ground that an application claiming one or more priorities contains one or more elements that were not included in the application or applications whose priority is claimed, provided that, in both cases, there is unity of invention within the meaning of the law of the country.
With respect to the elements not included in the application or applications whose priority is claimed, the filing of the subsequent application shall give rise to a right of priority under ordinary conditions.
4 G. (1) If the examination reveals that an application for a patent contains more than one invention, the applicant may divide the application into a certain number of divisional applications and preserve as the date of each the date of the initial application and the benefit of the right of priority, if any.
(2) The applicant may also, on his own initiative, divide a patent application and preserve as the date of each divisional application the date of the initial application and the benefit of the right of priority, if any. Each country of the Union shall have the right to determine the conditions under which such division shall be authorized.
Multiple and Partial Priorities in Japan
It is interesting that poisonous priority does not appear to exist in countries which have adopted into their national laws the provisions of Article 4 of the Paris Convention. Unlike Europe, United Kingdom, Australia, the United States and several other countries, the law in relation to priority entitlement in Japan conforms almost exactly with the provisions of Article 4 of the Paris Convention. The manner in which multiple priorities and partial priority is to be assessed is explained in some detail in Part IV of the "Examination Guidelines for Patent and Utility Models in Japan”, Japan Patent Office4. Chapter I of Part IV explains how priority is assessed under the Paris Convention, and includes a number of examples in Section 4.3 explaining how a single claim can be entitled to claim multiple or partial priorities.
Example 2 describes the situation in which a first application is filed claiming a chemical invention requiring an alcohol with 1 to 5 carbon atoms. However, the invention claimed in the Japanese application (which claims priority from the first application) specifies that the alcohol has from 1 to 10 carbon atoms. According to the explanation provided with the example, the priority date of the claim insofar as it relates to alcohols containing from 1 to 5 carbon atoms is the date of filing the first application. However, the priority date of the claim insofar as it relates to alcohols with 6 to 10 carbon atoms is the date of filing the Japanese application.
It will immediately be recognized that this scenario is analogous to Scenario 1 described above in which invention A represents the invention utilizing an alcohol having 1 to 5 carbon atoms, while invention A+ represents the invention utilizing an alcohol containing from 1 to 10 carbon atoms.
Multiple and Partial Priorities in Europe
While the European Patent Convention (EPC) seeks to implement the provisions of the Paris Convention, the language of its provisions does not correspond exactly with Article 4. Prior to commencement of the European Patent Convention in 1977, different European countries had different practices in relation to the treatment of multiple and partial priorities.
While some countries allowed a single claim to have more than one priority date, other countries did not. In view of the importance of harmonizing the treatment of priority entitlement, Fédération Internationale des Conseils en Propriété Industrielle (FICPI) made submissions to the effect that the EPC should include a provision to clarify that a single claim could have more than one priority date. This is now enshrined in the second sentence of Article 88(2) of the EPC which is discussed in further detail below.
FICPI’s submission was made to the Munich Diplomatic Conference of 1973 and was entitled “Memorandum C”5. The opening paragraph of Memorandum C put forward the proposal “that multiple priorities may be claimed not only in respect of one and the same application, but also in respect of one and the same claim of that application.” FICPI explained how such a provision would operate by drawing a distinction between two types of claims:
“AND” – claims (A + B); and
“OR” – claims (A or B).
The Memorandum then went on to explain the difference between these two types of claims.
The "AND" claim
Where a claim requires a presence of features A and B, and where feature A is first disclosed in a first priority application, P1, and the combination of features A and B is first disclosed in a second priority application, P2, a claim directed to the combination of A and B cannot enjoy partial priority from P1. This is because the combination of A and B was not disclosed in P1. The result is that a publication of A + B between the filing dates of P1 and P2 will destroy the novelty of the claim to A + B. However, a claim to A will enjoy the priority of P1, and a claim to A + B will enjoy the priority of P2.
The "OR" claim
Where a claim is directed to alternative features, A or B, and where feature A is first disclosed in a first priority application, P1, and feature B, as an alternative to feature A, is first disclosed in priority application P2, a claim to A or B will enjoy partial priority from P1 for feature A, and partial priority from P2 for feature B. The result is that publication of the invention with feature A between the filing dates of P1 and P2 will not destroy the novelty of a claim directed to features A or B. The Memorandum went on to explain that “it is of course immaterial whether the word “or” actually occurs in the claim, or is implied through the use of a generic term, or otherwise."
Memorandum C provided three examples explaining how priority dates would be assigned to “OR”–type claims.
Example a) (broadening chemical formula)
According to this example a first priority application, P1, discloses a narrow chemical formula with representative examples specifying that a substituent, R1, is chlorine. A second priority application, P2, is subsequently filed which discloses a broader chemical formula with additional examples justifying the broader scope. In P2 the substituent, R1, can be bromine, fluorine or iodine, as alternatives to chlorine. A European application (claiming priority from P1 and P2) is then filed which claims the broader chemical formula specifying that the substituent R1 can be halogen. The term "halogen" is a broad term encompassing chlorine, bromine, fluorine and iodine. According to the analysis of this scenario provided by FICPI, the claim in the European application should get the filing date of P1 as the priority date insofar as R1 is chlorine, and the filing date of P2 as the priority date for the other halogens, bromine, fluorine and iodine. The Memorandum explained that there should be no need to split the broad claim into multiple claims to ensure priority entitlement to P1 and P2.
Example b) (broadening of range)
According to this example a first priority application, P1, is filed disclosing a temperature range of 15 to 20°C. A second priority application, P2, is then filed disclosing a temperature range of 10 to 25°C. The European application is filed (claiming priority from P1 and P2) having a claim to the broader range of 10 to 25°C. According to the analysis provided in the Memorandum, the claims should get the filing date of P1 for the claimed invention insofar as it is carried out in a temperature range of from 15 to 20°C, and the filing date of P2 as the priority date for the temperature ranges of from 10 to 15°C and 20 to 25°C. The Memorandum explained that there should be no need to draw up separate claims for the three sub-ranges of temperature to allow priority entitlement from P1 for the narrower temperature range of 15 to 20°C.
Example c) (broadening of field of use)
According to this example a first priority application, P1, is filed disclosing a method for coating the inner wall of a pipe. A second priority application, P2, is filed disclosing the same method, but for coating inner walls of bottles or other hollow bodies. The European application is then filed (claiming priority from P1 and P2) having a claim to a method for coating inner walls of bottles or other hollow bodies. The Memorandum explained that the claim should get the filing date of P1 for the method insofar as it involves the coating of the inner wall of a pipe, and the filing date of P2 for the method insofar as it relates to the coating of inner walls of bottles or other hollow bodies, not being pipes. There should be no need to draw up separate claims for (1) the coating of inner walls of pipes, and (2) the coating of inner walls of bottles and other hollow bodies except pipes.
It is clear from the Travaux Préparatoires EPC 1973 that FICPI’s proposal was accepted and gave rise to the second sentence of Article 88(2) of EPC 2000 which appears below:
Multiple priorities may be claimed in respect of a European patent application, notwithstanding the fact that they originated in different countries. Where appropriate, multiple priorities may be claimed for any one claim. When multiple priorities are claimed, time limits which run from the date of priority shall run from the earliest date of priority.”
In view of the inclusion of this provision in the EPC, it is quite surprising that a poisonous priority situation could arise in Europe. It also strikes me as perverse that an applicant who relies on Article 4F of the Paris Convention in Europe, by presenting an application with claims relying on multiple priorities or partial priority, could find those claims anticipated by the applicant’s own divisional application filed in reliance on Article 4G of the Paris Convention. Yet, this is a direct consequence of poisonous priority.
How did poisonous priority arise in Europe?
It would appear that the first step towards poisonous priority in Europe was the decision, G 2/98, of the Enlarged Board of Appeal of the European Patent Office. This decision is generally regarded as the most important decision dealing with priority entitlement under the European Patent Convention. In it the Enlarged Board of Appeal looked very closely at the provisions of Article 88(2) and, in doing so, placed considerable reliance on FICPI’s Memorandum C. The Enlarged Board of Appeal summarized their conclusions as follows:
The use of a generic term or formula in a claim for which multiple priorities are claimed in accordance with Article 88(2) second sentence, the EPC is perfectly acceptable under Articles 80(1) and 88(3) EPC, provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters."
It is a restricted interpretation of the underlined section above that has opened the door for poisonous priority, since it appears to place a limitation on the circumstances in which multiple priority dates can be assigned. It is interesting that neither the EPC nor FICPI’s Memorandum C includes language suggesting that Article 88(2) second sentence, should only operate in limited circumstances.
It is clear from the reading of the decision that the Enlarged Board of Appeal, in providing this analysis of Article 88(2), second sentence, was not considering the relationship between this provision and the assessment of whole of contents novelty between parents and their divisionals, or European applications and their priority applications.
The door having been left open, a number of oppositions were run before the European Patent Office in which claims in patents were ultimately found to be anticipated by their parent applications, divisional applications, or priority applications6. A European patent (UK) was also found to be anticipated by its priority application in a recent decision of the Patents Court in the United Kingdom7. In most of these decisions the words of the Enlarged Board of Appeal in G 2/98, “provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters” were used to refuse the claims to multiple or partial priority.
At least insofar as the European Patent Office is concerned, it appears that interpretation of the language of the Enlarged Board of Appeal in G 2/98 has been revisited. In decision T 1222/11 dated 4 December 2012 the Technical Board of Appeal went to some length to explain how the language of the Enlarged Board of Appeal can be interpreted to give effect to FICPI’s proposal contained in Memorandum C. In doing so, the Board pointed out in paragraph 11.5 that they were “of the opinion as explained below that the condition, “provided that it gives rise to the claiming of a limited number of clearly defined alternative subject-matters", should be given, when read in its proper context, a different meaning than that attributed to it by the respective Boards in the above –mentioned decisions T 1877/08, T 0476/09, T 1443/05 and T 1127/00”. These decisions were previous decisions of the Technical Board of Appeal in which claims to multiple priorities or partial property were not recognized.
It is therefore quite unfortunate that, just when the European Patent Office has found a means for avoiding poisonous priority, poisonous priority should arise in Australia and New Zealand.
Multiple and Partial Priorities in Australia and New Zealand
Until 1969 it was necessary for an applicant for an Australian patent to indicate next to each claim the date the applicant considered to be the priority date of that claim. It was only possible to have one priority date for each claim. In view of this practice, much prosecution time was taken up splitting claims and arguing with the Examiner as to which date should be assigned to each claim. In an effort to improve the efficiency of the examination process, the Institute of Patent Attorneys of Australia made submissions to the Government in or about 1966 to the effect that this requirement should be removed8. However, after examining a first draft of the Patents Bill 1967 incorporating this amendment, the Institute realized that deletion of the requirement might have the unintended result that a claim relying on multiple or partial priorities might “only be entitled to the latest of the various applicable dates – i.e. the date on which the whole of the subject matter of the claim had been first disclosed (see Thornhill’s application 79 R.P.C. 199).” After pointing this out to the Government in a submission dated 21 February 19689 the Institute urged for the inclusion of a new provision “to provide that a claim may have, where appropriate, more than one priority date”. This submission was accepted and the Patents Act 1952 was amended to include new Section 44(2) which specified that a single claim could be entitled to multiple priority dates. This provision now appears in the Patents Act 1990 as Section 43(3):
Where a claim defines more than one form of an invention, then, for the purposes of determining the priority date of the claim, it must be treated as if it were a separate claim for each form the invention that is defined.”
It is also important to note that when the Patents Act 1990 came into force in 1991, the “prior claiming” approach to dealing with conflict between Australian applications and patents claiming the same or similar subject matter with different priority dates was replaced with European-style "whole of contents” novelty. Section 43(3) should have been effective in ensuring the claims relying on multiple priorities or partial priority would not be anticipated by corresponding divisional or parent applications, or applications filed on the same day by the same applicant claiming the same priority date or dates. Unfortunately, it wasn’t.
Although Australia has had a provision in its patent law since 1969 allowing a single claim to have multiple priority dates, it was not until the decision of Jagot J in Apotex Pty Ltd v AstraZeneca AB10 that the provision was subjected to judicial interpretation. While this decision related to three patents filed by AstraZeneca in respect of the pharmaceutical substance rosuvastatin, marketed as Crestor™, it was only Patent No. 200051842 (the Cation patent) that gave rise to the poisonous priority issue. This patent claimed a pharmaceutical composition comprising the active agent and an inorganic salt in which the cation is multivalent. The claims also included a proviso which can be largely ignored for the purpose of this discussion. The Cation patent claimed priority from UK Patent Application No. GB 0001621 (the '621 application) which disclosed a pharmaceutical composition containing the active agent in combination with a tribasic phosphate salt in which the cation is multivalent. On the same day they filed the Cation patent, AstraZeneca filed a second application in Australia claiming priority from the '621 application. The claims of the patent granted on this second application (the Crestor patent) were limited to the subject matter disclosed in the priority application, namely a pharmaceutical composition containing the active agent and a tribasic phosphate salt in which the cation is multivalent.
Although during prosecution of the Cation patent AstraZeneca attempted to include a proviso to exclude the tribasic phosphate salt compositions disclosed and claimed in the Crestor patent, the disclaimer was unsuccessful in achieving this result. While the priority date of the claims of the Crestor patent was clearly the date of filing the '621 application, Jagot J was not prepared to recognize partial priority in respect of the claims in the Cation patent which encompassed some of that subject matter. The result was that the claims in the Cation patent were considered to be anticipated by the Crestor patent.
Although Jagot J was referred to Section 43(3) by Counsel for AstraZeneca, she accorded a later priority date to each claim of the Cation patent, even though the claims encompassed, and were found to be anticipated by, the subject matter disclosed in the Crestor patent. The decision contained very little in the way of an analysis of the wording of Section 43(3).
AstraZeneca appealed the decision to the Full Federal Court, where the matter was considered by an enlarged panel of five Judges11. The main basis of the appeal was in relation to the assessment of inventive step, this being the reason the matter was heard by five judges instead of the usual three, but the Full Court was also required to consider the interpretation of Section 43(3). Although discussion of Section 43(3)12represents obiter dicta, it carries substantial weight since all five judges were in agreement on this point. Their comments also support the earlier interpretation of the provision by Jagot J.
The Full Court acknowledged that the provision corresponded to Section 44(2) which was introduced into the 1952 Act in 1969 to make provision for the attribution of different priority dates to "different alternatives comprised in a single claim", but they interpreted the provision in a way which gives the provision little effect.
It is apparent that the Full Court considered the submissions made by the Institute of Patent Attorneys in Australia in 1968 (mentioned above) because they made reference to the decision in Thornhill’s application, a decision mentioned in the submissions made by the Institute. Unfortunately, they incorrectly assumed that the provision was introduced solely to address the particular problem encountered in Thornhill’s application.
Thornhill’s application was an old United Kingdom “prior claiming” case decided under the Patents Act 1949 (UK). The invention described in the provisional application was a process for making a black tea concentrate involving four main steps, abbreviated in the decision as steps a+b(i)+c+d. The complete application, which claimed priority from the provisional application, described the same process but included an alternative for step b(i), namely step b(ii).
Claim 1 of the complete application included both alternatives, and, accordingly, the Hearing Officer in the UK Patent Office notionally re-wrote the claim as two sub-claims:
Sub-claim 1A = a+b(i)+c+d
Sub-claim 1B = a+b(ii)+c+d.
Although the Hearing Officer was prepared to assign the filing date of the provisional to sub-claim 1A, and the filing date of the complete application to sub-claim 1B, on appeal the whole claim was given the later date. In the AstraZeneca decision the Full Federal Court formed the view that the provision, which is now Section 43(3), was introduced to deal with the situation where alternatives are explicitly defined within a claim, or where different forms of the invention are claimed in dependent claims. The Full Court referred to claim 3 of the Cation patent as an example of a claim in this form. Claim 3 specified that the multivalent cation can be selected from “calcium, magnesium, zinc, aluminum and iron”.
Unfortunately, the Full Court was unable to relate variants, which they acknowledged were encompassed by the claims of the Cation patent, to "more than one form" of the invention as referred to in Section 43(3):
In our view, claim 1 of the 842 or Cation patent does not define more than one form of the invention. Unlike the claim in issue in Thornhill’s application, claim 1 of the 842 or Cation patent does not by its terms allow for any alternatives or, adopting the language of s43(3), different forms of the invention. Claim 1 defines only one form of the invention even though there will be a number of potential variants that are within its scope. We do not think s43(3) is intended to treat every potential variant of the defined invention as if it was a form of the invention that must be treated as a separate claim which is to be given its own priority date. Rather, it is intended to deal with very different situations such as that which arose in Thornhill’s application or where, to take a slightly different example, a claim is dependent on one or more independent claims (claim 3 of the 842 or Cation patent takes this form) each of which has a different priority date.”
Accordingly, it would appear that the Full Federal Court of Australia has adopted an interpretation of Section 43(3) that is not unlike the restricted interpretation of Article 88(2) EPC adopted by a number of Technical Boards based on the “limited number of clearly defined alternative subject-matters” language of the Enlarged Board of Appeal. However, unlike the European Patent Office which can now follow the more generous interpretation applied in decision T 1222/11, it would seem that legislative amendment will be required to remedy the situation in Australia.
Interestingly, prior to this decision of the Full Federal Court of Australia, the Institute of Patent and Trademark Attorneys of Australia (IPTA) and IP Australia were urging the New Zealand Government to amend the Patents Act 2013 to include a provision corresponding to Section 43(3) which would allow a claim in a New Zealand patent subject to the new law to have more than one priority date. It was hoped that this would be done prior to commencement of that Act on 13 September 2014. It is perhaps, now, good fortune that a provision corresponding to Section 43(3) was not introduced.
Under the New Zealand Patents Act 2013 it is only possible for a claim to have a single priority date, and that date will be the date upon which all of the subject matter within the claim was first disclosed. Accordingly, in the case of multiple or partial priorities, the priority date of the claim will be the later of the various dates. New Zealand has also adopted a "whole of contents" approach to the assessment of novelty to replace the prior claiming approach of the previous Patents Act 1953. The result is that the filing of a divisional application will immediately create novelty destroying prior art for any claim in the parent patent which relies on multiple or partial priorities. Similarly, any claim in the divisional which relies on multiple or partial priorities will be anticipated by the parent patent. There are signs that this problem has now been recognized in New Zealand and that progress might be made towards amending the legislation to remove the problem. It is also hoped that similar steps will be taken in Australia to address the problem created by the recent decision of the Full Federal Court.
What is the cure for poisonous priority?
Until the laws in Australia and New Zealand are amended, applicants and patentees will need to either live with the uncertainty surrounding the validity of claims in patents and patent applications relying on multiple or partial priorities, or take steps to remove the problem. While the problems caused by the Patents Act 2013 in New Zealand will only apply to applications filed and granted under the new law, the decision of the Full Federal Court of Australia impacts on all patents previously granted which are parents or divisionals, or which are filed at the same time claiming the same priority, and which include claims which rely on multiple or partial priorities. Any amendments to the legislation will need to operate retrospectively in order to restore the validity of these claims.
Another option which can be considered by applicants and patentees is to split affected claims into multiple claims so that each sub-claim is entitled to a single priority date. It would also be possible to amend patents and applications to include new claims relying on a single priority date, while leaving the original claims in place. In Australia, there is also the option of rewording the claim in a form similar to the claim in Thornhill’s application. However, I expect that in many cases such amendments will be difficult or impossible, or in some cases impractical. To take an example, how would one “fix” a claim such as that described as Example (b) in Memorandum C? One possibility might be to split the claim into three claims as follows:
15° to 20° (entitled to priority date P1).
Greater than 20°C up to 25°C (entitled to priority date P2).
10°C up to less than 15°C (entitled to priority date P2).
Alternatively, it may be possible to amend the claim as per Thornhill’s application to refer to "10°C up to less than 15°C or 15°C to 20°C or greater than 20°C up to 25°C". However, the claim could still be vulnerable since the test for priority entitlement, whether it be a fair basis test or an enablement test, might extend priority entitlement beyond the actual temperature ranges disclosed. For example, the original disclosure of 15°C to 20°C in P1 might actually provide fair basis (or enablement in the case of patents subject to the Raising the Bar Act in Australia)13 for a claim directed to a range of 14°C to 21°C.
Separating or splitting claims which are subject to the provisions of the Raising the Bar Act based on priority entitlement will be particularly difficult because there is currently no case law in relation to the way in which the new enablement test for priority will be assessed. Under the provisions introduced by the Raising the Bar Act, a claim must be supported by the specification. However, for the assessment of priority the claim does not need to be supported by the priority application. Instead, the priority application must disclose the invention in the claim “in a manner that is clear enough and complete enough for the invention to be performed by a person skilled in the relevant art”. It will be recognized that this language is very similar to the newly introduced requirement for sufficiency or enablement. This is a highly unusual test for priority and, while many jurisdictions have an “enablement” component to their test for priority entitlement, I doubt whether many would have a priority entitlement test based solely on enablement. There will be similar problems in New Zealand since the Patents Act 2013 introduced a new "support" test for priority to replace the previous fair basis test. It remains to be seen how the new test will be applied by the New Zealand Courts. A further problem to deal with in New Zealand in the case of divisionals is the restrictive assessment of double patenting, particularly between parents and divisionals, where the scope of claim of one patent falls wholly within the scope of a claim of another. This makes it difficult in New Zealand to obtain multiple patents having different claim scopes.
The patentability of inventions in most jurisdictions is judged with reference to the prior art as it existed before the priority date. Prior to filing a patent application, it is common to assess the available prior art so that a decision can be made as to the likelihood of the application proceeding to grant. It would be an extremely perverse outcome, and one that would do little to encourage innovation and the disclosure of inventions through patent publications, if the patent system allowed patentees and applicants to invalidate their own patent applications through the very steps they take to seek patent protection for their inventions. Patent applicants should be able to rely on the Paris Convention, and the provisions supporting multiple and partial priorities and the filing of divisionals, as they take the necessary steps to obtain the patent protection to which they are entitled.
It is also important to note that Article 4F is not only relevant in the context of poisonous priority. Article 4F is important to ensure that the prior art base against which patentability is judged does not include publications or filings by third parties which occur after the priority date which should be assigned to a particular part of a claim which claims multiple or partial priorities. It is hoped that once Australia and New Zealand amend their legislation to remove poisonous priority that it will not resurface in any other jurisdictions. However, in the meantime it would be an interesting exercise to review patent laws currently in force in various countries and regions to ensure that they comply fully with Articles 4F and 4G of the Paris Convention.